KNN-交叉验证选择k

def solve():
    import pandas as pd
    import numpy as np
    from sklearn.neighbors import KNeighborsClassifier
    from sklearn.model_selection import cross_val_score
    df = pd.read_csv(____)
    X = df.drop(____)
    y = df['____']
    best_k = ____
    best_score = ____
    for k in range(____, ____):
        knn = KNeighborsClassifier(____)
        scores = cross_val_score(____)
        if scores.mean() > best_score:
            best_score = scores.mean()
            best_k = k
    print(____)
    print('____', round(____))